Particle Trail Tracked Around Footage

If you want particles to fly in front of and behind people, you will need to do some rotoscoping. If the camera is moving, you will also have to do some tracking. Mocha AE, AE's Camera Tracker, Mocha Pro, or Syntheyes may be required- it all depends on the shot. 

It is pretty simple to use expressions to adjust the scale of 3D layers to match the original 2D image so you can move the Particle emitter around in 3D space. Combine that with some tracking, and you can build your stage and fly the particles anywhere you want them to go.

If you have not shot the footage yet, some careful planning can save you hours of work. Not all shots will work, and difficult shots may require dozens or even hundreds of hours more to complete than shots that are easy to track, create mattes, or rotoscope. The last moving camera shot I worked on that needed effects to go between people, vehicles, and buildings required about 40 layers and took the better part of a 12-hour day. 

If you can, show us the shot, and we can give you some ideas. The only thing I know for sure is that it will take at least one masked, rotoscoped, tracked, or keyed copy of the original footage to put your particle stream behind anything.

I've found Particular sometimes has issues with the graphics card so that might explain the issues.  I have also noticed the Aux particles can really slow it down.

I'm a big fan of the included CC Particle World, although I will admit there's a learning curve to it.  

To link Particular to tracking data, you'll need to create a light named "Emitter".  A light is a 3D object so if you use camera tracking to generate a 3D camera, then the light will be in 3D space.

For CC Particle World, you can use expressions to link your particles to a 3D null and then it will work the same way.

These two tutorials might help with CC Particle World:

https://www.youtube.com/watch?v=dYYmeBOWXpw

https://www.youtube.com/watch?v=Gdlvx_8DYfs 

Without seeing your footage and storyboards any discussion is pretty much pointless. And if Particular "grinds your machine to a halt" you either have overcranked your settings or there's a compatibility issue with e.g. the OpenGL particle renderer/ preview. Either way, you have not provided nearly enough info, screenshots, actual systzem specs etc. to even begin to make sense of this. Without any of this it only ends up as pointless guess work.

Mylenium